I'm wondering if there is any AY codec around, that would create AY register dump files from raw audio.
I know there are some apps that play 4/5 bits PCM, but I think it could be possible to do things differently, with a codec similar to mp3 encoders...
It would FFT the signal, select the 3 biggest freqs (it's basically the job of an mp3 encoder to select the best frequencies) and the corresponding enveloppes and produce the closest register data flow. It would also likely be less intensive for playback.
But I'm not sure the result would be good enough.
Maybe I should have a try at hacking this in ffmpeg (along with a SID codec, that's quite similar). But I'm too tired atm.